This is an application for an ADAMHA Research Scientist Development Award (K02). The purpose of the Award is to foster the continued scientific development of the Principal Investigator (P.I.) in understanding the psychobiology of sleep related to psychiatric disorders. Research to be performed during the period of support includes a basic study of the acute effects of light on sleep and temperature in rats. Light therapy is being used with increasing frequency to treat a variety of conditions, including depression, circadian rhythm disorders, and sleep disturbances related to aging. Although the mechanisms for light entrainment of circadian rhythms have been studied extensively, the mechanisms for acute photic effects on sleep and temperature are unknown. A better understanding of light effects on the nervous system could make light a more powerful clinical tool.